Telecommunications operators have on-line billing/rating systems that need to respond in near real-time to events generated by an associated telephony network. Since the rating system is part of the telephone call-path, the rating system should be highly available. For example, the rating system should be available to respond to the event within a very short response time. Furthermore, the rating system should ensure data reliability such that each rated event, as well as customer balance, is saved (persisted) by the system. There is thus a need for addressing these and/or other issues associated with the prior art.